Mountain gorillas are found in 3 countries in Africa: Rwanda, Uganda, and the Democratic Republic of the Congo(DR Congo). The gorillas live in a tiny area where these countries' borders meet, which is on the western edge of the East African Rift Valley. Their habitat is only about 780 sq km. This is an area smaller than some individual cities like London, New York City, and Los Angeles!

There are two separate populations of mountain gorillas, each of which live in their own small patch of afromontane forest about 40 km from each other. The forests were once connected. However, it is believed that they became separated about 500 years ago by people clearing the forests for wood and farmland. This area is now occupied by towns, farms, and roads, so it is impossible for the gorillas to migrate between these two islands.

When you think of an island, you think of land that is surrounded by water, right? Actually, an animal’s habitat that is surrounded by unsuitable habitat can be considered an island too. And just like an animal is ‘’trapped” on an island in the ocean, gorillas are not able to leave these small areas of forest that have not yet been cleared by loggers or farmers.

These two islands are different in many aspects, including their origins, soil, plant life, elevation, and endemic species of animals. Because of these differences, especially the vegetation on which the gorillas feed, some primatologists think that they are splitting into two separate subspecies. However, the differences are extremely minor since 500 years of separation is not enough time to evolve different characteristics.

One population lives on the steep slopes of 8 extinct volcanoes where the borders of the 3 countries above meet. They are called the Virunga Mountains. Virunga means “a lonely mountain that reaches the clouds”. Each of these countries have their own national park in the Virunga Mountains and are contiguous. The Virunga National Park in the DR Congo (a UNESCO World Heritage in Danger site), the Volcanoes National Park in Rwanda, and the Mgahinga Gorilla National Park in Uganda. The highest volcano is 4507 meters high.

The vegetation is thickest in the lower elevations and gradually lessens the higher you go. Most mountain gorillas here live between 2500 and 4000 meters, which can be freezing at times and include hail and snow. The black soil of the Virungas comes from volcanoes, so they are rich in minerals. This provides enough nutrients for the plants to grow so densely that some have described their habitat as a salad bowl. These verdant woodlands are the cloud forests made famous in the movie “Gorillas in the Mist”, which is the story of Diane Fossey.

Some of the other large animals that live in the Virungas are duikers, forest elephants, giant forest hogs, forest buffaloes, bushbuck, golden monkeys, and blue monkeys. Carnivores include leopards, golden cats, servals, spotted hyenas, and side-striped jackels. They are all mainly nocturnal. Lots of birds, including the spectacular rwenzori turaco, and the grey crowned crane also thrive in the gorillas’ habitat.

The other population lives in the Bwindi Impenetrable Forest, which is also a UNESCO World Heritage site, but is not on their in danger list. Although both were created by continental rifting, they differ in several ways. Bwindi was created by uplift of the earth crust through tectonic movement and not as a result of volcanic activity. The erosion that followed deposited tons of minerals that later became rich red earth, which now lies beneath spongy forest humus. The lower valley bottoms also contain lots of clay, which doesn’t allow water to drain, and so there are many swamps. These swamps, along with the dense vegetation, are almost impossible for humans to walk through, thus the name Impenetrable.

Bwindi is also lower in elevation than the Virungas and tops out at 2,607 meters. Most mountain gorillas here live between 1,100 and 2,600 meters, It has remained a forest for millions of years while most other forests in Africa have come and gone due to climate change throughout the ages. Because of this, it is home to more than 350 species of birds, 200 species of butterflies, and 100 species of mammals. 10 species of primates make Bwindi their home, including about half of the world’s population of mountain gorillas.

Some of the animals that live in Bwindi are duikers, forest elephants, forest buffaloes, bushbuck, tree hyraxes, giant forest hogs, golden cats, striped jackels, and clawless otters. Primates include chimpanzees, blue monkeys, red-tailed monkeys, black and white colobus monkeys, vervet monkeys, and olive baboons. Beautiful birds, including the great blue turaco, ross's turaco, and the crested guinea fowl live in the forest, along with chameleons, frogs and insects.

Due to their proximity, both the Virungas and Bwindi share a common climate. There is a lot of precipitation where mountain gorillas live, more than 200 centimeters annually. The air is misty, damp, and cool, especially during the wet seasons, which are during March and April, and September through December. There are also two dry seasons: January – February and May – August. Temperatures range from 4° - 15° Celsius, though they may reach 26° C. When its raining heavily, the gorillas become dormant. Their pear shaped bodies minimize the surface area exposed to the elements. This, along with their thick fur, allow them to stay warm, even in cold, wet conditions.

adj. Of an animal, lying asleep or as if asleep; inactive.
Gorillas will sit down, arms crossed and motionless
while it rains. Photo courtesy of www.hoothollow.com

Although they look like dogs, spotted hyenas are more closely related to cats. Their babies are
born with their eyes open! Photo courtesy of Loot Eksteen

Side-striped jackals are nocturnal. They are very adaptable to different environments
because of their omnivorous diet. These opportunists will scavenge or hunt wide variety
of food including rabbits, rodents, carrion, fruit, maize, reptiles, eggs, and birds.
Photo courtesy of Kay Myers

Turacos have an outer toe on each foot that can face either
forwards or backwards. When roosting, they have three toes
facing forward to increase the hold of a perch. When running
along branches, two toes point forward and two backward
for increased agility.
Photo courtesy of Nik Borrow

78° F

If you live in a dark green area, you get about the same amount of precipitation as the gorillas do.
Map courtesy of www.nationalatlas.gov

The word "jungle" comes of the Indian Sanskrit word jangala, which means any
kind of wilderness. People commonly call any kind of lush, dense forest near the
equator
a jungle,but biologists prefer the term forest. Photo courtesy of Philip Kromer via CC BY-SA 2.0

Because leopards are slow eaters, they drag their prey up into
trees to keep it from other predators and scavengers. That prey
can be 2 to 3 times their weight! Photo courtesy of Loot Eksteen

Crested guinea fowl males will run great distances back to their mate
to place a morsel of food at her feet. Photo courtesy of Loot Eksteen

Chimps are smart! They eat medicinal plants to treat themselves
for illness and injury. Young chimps learn to make tools by
watching others; they use sticks to extract termites to eat and
crumple leaves to soak up water to drink. They can also recognize
themselves in a mirror. Photo courtesy of Frank Wouters
via CC BY 2.0

Turacos are the only birds to have true red and
green color. When you look at most birds, the color
you are seeing is a reflection produced by the
feather structure. The turaco's red and green
pigment both contain copper. If you put a red turaco
feather in a glass of water, it would turn pink!
Photo courtesy of Guru Pawan.

The 200 cm (80 inches) of rainfall Bwindi receives every year supplies Uganda with 6% of its water supply.
Despite all this water, gorillas avoid going into it and almost never have to drink because the plants they eat
contain so much liquid. Photo by Tony Hartman.

In the local language of Lukiga, Bwindi means “a muddy,
swampy place full of darkness”. Photo by Tony Hartman.

The tree hyrax is nocturnal. Its closest living relative is the elephant.
Photo courtesy of Rhett A. Butler

Continental rifting occurs when magma pushes up into the upper mantle,
causing the brittle crust to rupture. This lifts the edges up to create mountains
such as those at Bwindi. Smaller fissures allow some magma to rise to the
surface, creating volcanoes such as those of the Virungas. Diagram back-
groundcourtesy of the University of Leicester and altered by igorilla.org.

Black and white colobus monkeys use branches like a trampoline to catapult
themselves onto higher branches. The babies are pure white for the first few
weeks of their lives.
Photo courtesy of M. Karstad.

Some Vervets lie! Males sometimes attract females by saying
the word for food. However, it turns out they have nothing to
offer but love.
Photo courtesy of Doug Wheller via CC BY 2.0

n. The natural home or environment where
an animal, plant, or organism lives.

The East African Rift Valley began forming about 65 million years ago in a
process called continental rifting. The rifting caused a fracture in the earth’s
crust that is constantly widening and slowly splitting the African continent
into 2 parts. Notable features of the rift are Mt. Kilimanjaro, the tallest
mountain in Africa, Lake Tanganyika, the second deepest lake in the world,
and Lake Victoria, the third largest lake in the world. The red dot marks
where the mountain gorillas live. Map courtesy of geology.com

80 inches

n. Any form of water, such as rain, snow, sleet,
or hail, that falls to the earth's surface.

n. The state of being near or next to something.

The great blue turaco has a very loud call and is related to hummingbirds
and owls. Photo courtesy of Robert Photography

Olive baboons have a dog-like muzzle. They can live to be 30 years old, and
use over 10 different vocalizations to communicate with each other
.
Photo courtesy of Ferran J. Loret

Von Hohnel's chameleons change their color to reflect their emotional state and to attract mates, not as
camouflage. Photo courtesy of Ferran J. Loret

Grey crowned cranes will sometimes fake an injury to lure predators away from their nests. It
is the national bird of Uganda. Photo courtesy of Ang Hwee Yong.

Golden monkeys are found nowhere else on earth but the bamboo forests of
the Virungas.
Photo courtesy of Ferran J. Loret

Bushbuck mothers hide their newborns in the bushes
and eat their dung to make sure no scent remains to
attract predators
.
Photo courtesy of Ferran J. Loret

The red-tail monkey has cheek pouches to store food in while it travels.
Photo courtesy of Ferran J. Loret

Blue monkeys are not really blue. Because they have little hair on their faces, they sometimes
have a blue appearance.
Photo courtesy of Ferran J. Loret

Forest buffalo have horns that are smaller and straighter than the African
buffalo. They also angle
back so they don't get tangled in the dense foliage
of the forest. Photo courtesy of Valter Jacinto via CC BY-NC-SA 2.0

Giant forest hogs can weigh up to 275 kg. (600 lbs.) and are almost as big
as donkeys! Photo courtesy of Sandra Schlesinger.

Sabyinyo volcano in the Virungas. Sabyinyo means "old man's teeth" due to its
jagged ridges
. This is the volcano where mountain gorillas were first seen by
Robert von Beringe in 1902. Unfortunately he shot and killed 2 of them.
Mountain gorillas got their scientific name from this German army officer.
Photo courtesy of Youngrobv

There are only about 20 left in Bwindi. These forest elephants differ from
bush
elephants in that they are smaller and have rounder ears and straighter tusks.
Photo by Thomas Breuer, courtesy of PLOS via CC BY SA 2.5

The name “Duiker” means “diver” in the South
African language
Afrikaans, and refers to the
antelope’s habit of diving under bushes when
threatened. Photo courtesy of Shebta via CC BY-NC 2.0

4,000 and 8,000 feet

8,551 feet

n. A brown or black organic substance made from decayed
vegetable or animal matter that provides nutrients for plants
and increases the ability of soil to retain water.

n. Natural processes, including weathering,
abrasion, and corrosion, by which material
is worn away from the earth's surface.

adj. Relating to, causing, or resulting from
structural deformation of the earth's crust.

adj. Impossible to penetrate or enter.

adj. Sharing an edge or boundary; adjacent.

One of 31 properties worldwide which the World
Heritage Committee has decided to include on
the List of World Heritage in Danger sites. 5 are in
the DR Congo. View the entire list at unesco.org

A cloud forest is a tropical forest, often near peaks of mountains, that usually has constant cloud cover
throughout the year. Photo by Tony Hartman.

8,200 and 13,100 feet

14,787 feet

v. To develop gradually, especially from a simple to
a more complex form: humans evolved from apes.

n. A person who studies primatology, which is the
branch of zoology that deals with primates.

This is a false color radar image taken from the space shuttle Endeavor in
1994 showing the "island" of the Virunga range of volcanoes surrounded by
farmland and villages (purple areas).The
faint lines in purple are terraced
fields. Photo courtesy of NASA.

adj. A term used to describe the plant and animal species common
to the mountains of Africa and the southern Arabian peninsula.

v. When an animal or person moves from
one region or habitat to another.

25 miles

Mountain gorillas live about
1000 km away from the western lowland gorillas and were separated from them 2-3
million years ago.
Over time, they evolved differently and are now considered a separate species. Map background
image courtesy of Google, Inc., and altered by igorilla.org.